1. Field of the Invention
This invention relates to accumulators employed in rolling mills to temporarily accumulate and decelerate hot rolled products. Examples of such accumulators are described in U.S. Pat. Nos. 7,021,103 and 7,093,472, the descriptions of which are herein incorporated by reference.
2. Description of the Prior Art
In accumulators of the above-mentioned type, as depicted diagrammatically at 10 in FIGS. 8 and 9, a curved guide 12 has an entry end 12a aligned with a first axis A1 to receive a hot rolled product traveling at a first velocity V1. The guide has an exit end 12b spaced radially from axis A1 and orientated to deliver the product in an exit direction along a second axis A2 transverse to axis A1. The guide 12 is rotatable about axis A1 in a direction opposite to the exit direction of the product and at a speed at which its exit end 12b has a second velocity V2 lower than velocity V1. The product is thus delivered from the exit end 12b as a helical formation of rings R at a third velocity V3 equal to V1−V2.
A cylindrical drum 14 is arranged to axially receive the rings R. The drum is rotatable about axis A1 in a direction opposite to the direction of rotation of guide 12 and at a speed such that the product is unwound from the drum at velocity V3.
A receiving means in the form of a catcher 16 receives the product being unwound from the drum and serves to direct the product to other equipment (not shown) for further processing. The catcher is movable in opposite directions along a path parallel to axis A1 in order to maintain its alignment with the product being unwound from the drum.
Ideally, the mill control system will maintain a balanced relationship between the rotational velocity V2 of the delivery end 12b of the curved guide and the incoming velocity V1 of the product, with the objective being to provide the accumulating rings R with inner diameters only slightly larger than the diameter of the drum surface. This in turn will minimize frictional resistance to the gradual shifting of the rings along the drum surface in the direction of axis A1, while also maintaining a stable helical ring pattern on the drum.
In practice, however, velocity V1 may undergo sudden and random variations due to unsteady rolling conditions in the mill. If the mill control system is incapable of reacting to such variations with sufficient speed, the diameters of the rings may either increase or decrease to an undesirable extent. If the rings become too small, resulting in the product being tightly wound on the drum, the resulting frictional resistance will impede shifting of the rings along the drum surface. On the other hand, if the rings become too large, the helical ring pattern may be upset, leading to difficulties in unwinding the product from the drum.
The objective of the present invention is to provide means for dealing with both of these potential problems.